Edge-Exfoliated Graphites for Facile Kinetics of Delithiation

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• 作者：Jeong-Seok Park ; Myeong-Hee Lee ; In-Yup Jeon ; Han-Saem Park ; Jong-Beom Baek ; Hyun-Kon Song
• 刊名：ACS Nano
• 出版年：2012
• 出版时间：December 21, 2012
• 年：2012
• 卷：6
• 期：12
• 页码：10770-10775
• 全文大小：371K
• 年卷期：v.6,no.12(December 21, 2012)
• ISSN：1936-086X

文摘

As high rate charge and discharge characteristics of energy storage devices become more important with the market of electric vehicles intensively growing, the kinetics of lithiation or delithiation of electrode materials for lithium ion batteries require enhancement. Graphites, the most widely used anode materials, have a limited power density at high discharge rates, while their alternatives, such as silicon and transition metal oxides, show even inferior rate capability. This work was motivated from an idea of what if the edge opening of graphite was zipped more open to lithium ions in the electrolyte. By edge-selective functionalization, the peripheral d-spacing of graphite (d₀) was locally controlled. Larger values of d₀ led to higher capacity especially at high discharge rates. Around 2-fold enhancement of capacity or energy density was achieved at 50C discharge rate from 110 to 190 mAh g^鈥? by exfoliating graphite locally in its edge region. Also, the d₀ dependency of delithiation kinetics confirmed that the electrochemical step of Li⁺ influx into or efflux out of the interlayer space of graphite is possibly the rate-determining step of lithiation or delithiation.

Keywords:

graphites; interlayer spacing; nanostructure; lithiation; lithium ion batteries; anodes